THE CAUSE or MIMETIC RESEMBLANCE ETC. 571 



kinds happen to possess stings — that the central types in the 

 groups of butterflies belong to subfamilies which are more 

 abundant and even more unpalatable than the generality of their 

 order. It is, furthermore, a mere coincidence that such groups 

 are formed round the Danaincd and AcrceincB, wlierever they occur 

 in all the warmer regions of the world, and in tropical America 

 also round the Ithomiince {NeotropincB) , wliich are closely related 

 to the former, and the SeliconinaB, which are closely related to 

 the latter. 



No theory except natural selection explains why the number 

 of colours and patterns in the dominant groups of butterflies 

 mentioned above are so few in relation to the number of species, 

 as was pointed out by Prof. Meldola (Ann. & Mag. Nat. Hist., 

 Dee. 1882). These colours and patterns have been recently 

 studied very carefully, especially in the IthomiincB, by A. Gr. 

 Mayer (Bulletin of the Mus. of Comp. Zool. at Harvard Coll., 

 Feb. 1897, p. 169). Mayer shows that "the 200 species of 

 Papilio in South America display .36 distinct colors, while the 450 

 species of Danaoid HeliconidcB \_Ithomiin(je^ exhibit only 15. 

 Hence the numbers of the species and of the colors are almost in 

 inverse ratio in the two groups. Tbis may be explained by the 

 fact, that the Danaoid Seliconidce mimic one another, while the 



Papilios do not There is no lack of individual variability 



among the species of the Danaoid Heliconidce ; yet the species 

 as a whole vary but little from the two great types of color- 

 pattern represented by Melincea and Ithomia. In order to 

 account for this remarkable fact, I am forced to resort to Fritz 

 Miiller's theory of mimicry " (I. c. p. 229). Again on page 225 

 Mayer remarks : " It is difficult to account for the remarkable 

 conservatism in respect to color-variations among the Keliconidce 

 [here used, as in Bates's original paper, to include Danaince, Itho- 

 miincB, and Seliconina;'], unless we resort to the explanation 

 afforded by the theory of mimicry ; for, while there is such 

 remarkable simplicity and uniformity of color-pattern throughout 

 the wholj group of the Heliconidce, individual variations are very 

 common." 



It is not from any predisposition or bias in favour of natural 

 selection that these conclusions are reached, but simply because 

 natural selection off"ers an explanation of so many remarkable 

 facts which are iitterly meaningless under any other theory yet 

 brought forward. 



